Drop-out fuse



w. SQHULTZ Er A1..

Feb. 4, 1936 DROP-OUT FUSE 2 sweats-sheet 1 Filed Fem 23, 1955 Feb. 4, 1936. W, Q SCHUL-[Z EVAL 2,29,5l93

DROP-OUT FUSE Filed Feb. 23, 1955 2 Sheets-Sheet 2 RNEY.

Patented Feb. 4, 1936 UNITED STATES PATENT OFFICE DROP-OUT FUSE William O. Schultz, South Milwaukee, and Alwin G. Steinmayer, Milwaukee, Wis., assignors to Line Material Company,

South Milwaukee,

This invention relates to drop-out fuses.

In general, this invention is an improvement over that .disclosed in the copending application of William O. Schultz for Fuses, Serial No. 650,- 815 led January 9, 1933.

Objects of this invention are to provide a novel form of drop-out fuse which may be of the housed type, but which is so constructed that the fuse and door both drop out when the fuse blows under overload.

When a fuse blows under short circuit conditions, the pressure builds up in the tube very rapidly so that the combined melting and arcing time is very short, for example in the neighborhood of a half cycle. As a result the arc is extinguished inside of the tube almost the instant the fuse tube starts to swing away from its contacts.

On the other lia-nd when a fuse blows on overload or slow burning conditions, the current is limited and as a result compression builds up in the tube relatively slowly. As a result several cycles may elapse between the actual melting of the fuse and the time at which the arc is extinguished. During this arcing time the fuse, when of the drop-out fuse type, is swinging away from its contact with the result that if the arc is not extinguished inside the tube, burning will occur between the contacts of the housing and those of the fuse.

This invention is designed to overcome the above noted defect, and objects of this invention are to provide a novel form of drop-out fuse in which the construction is such that it permits the fuse tube to continue to swing outwardly and yet retains electrical contact with the brush or other contact, so that ample time is provided even under slow burning conditions and under small overloads.

Further objects are to provide a construction having the features hereinabove outlined which nevertheless provides an insulated hinge construction for the lower portion of the fuse tube assembly so that when the fuse tube assembly swings to open position after blowing of the fuse link, all parts of the fuse tube assembly are dead, or. in other words, electrically disconnected from both sides of the line.

Further objects of this invention are to provide a novel form of contact or arcing nger which is spring urged outwardly to maintain contact with the stationary contact for a predetermined length of time, as outlined hereinabove, which also assi-ts in the initial opening motion or dropping motion of the fuse assembly, and which acts as a cushion to cushion the falling fuse tube assembly.

Further objects are to provide a novel form of drop-out fuse construction in which the contact nger hereinabove described may also assist in the withdrawal of any remaining portion of the fuse link after the fuse link hasruptured, which will, therefore, increase the spacing between the ends of the fuse link, such action being particularly desirable on small overloads or slow burning conditions.

Further objects are to provide a construction in which means are provided to insure the holding of the fuse tube assembly to the housing after the fuse tube assembly swings outwardly so that there is no possible vchance of inadvertent disconnection occurring between the fuse tube assembly and the housing, the construction, however, permitting free removal and replacement of thefuse tube assembly.

Further objects are to provide a housed type of drop-out fuse in which the fuse tube assembly includes the door ofthe housing and the fuse tube, in which the doormay be pulled open and thereby may carry with it the fuse tube and disconnecting the fuse tube from the line, if it is so desired, limited motion being provided between the fuse tube and door, detaching means being provided to permit the direct opening of the door by an outward pull thereof.

Further objects are to Vprovide a simple and reliable type of construction which is cheap to make, which has relatively few parts, and which may be readily re-fused, and which will give a visual indication when the fuse has blown.

Embodiments of the invention are shown in the accompanying drawings, in which:

Figure l is a vertical sectional view through the device showing the device in operative position in full lines and showing successive positions occupied by the fuse tube assembly after the fuse link has blown.

Figure 2 is a rear face view of the lower contact arm and contact nger and associated parts.

Figure 3 is a sectional view on the line 3-3 of Figure 1. v

Figure 4 is a fragmentary view showing a further form of the invention.

Figure 5 is a rear face view of the construction shown in Figure 4.

Referring to Figure 1, it will be seen that a housing l is provided with an upper terminal member 2 and a lower terminal member 3 which carry upper and lower brush contacts 4 and 5.

The housing is provided with a barrier 6, in accordance with the usual practice,` between the upper and lower stationary contacts and is provided with a pair of hinge members 'I which are electrically distinctr and separate from` the stationary contacts of the housing. These hinge members are each provided with hook like portions 8 and with inwardly projecting stops or shoulder portions 9. The housing is provided with a door I0 which may have a manipulating eye or handle portion I I and which is provided 'with projecting ears I2 between which the lower collar I3 of the fuse tube I4 is pivoted. A spring I5 is carried by the door and bears against the lower portion of the fuse tube so as to tend to rock the fuse tube in a clockwise direction, as viewed in Figure 1', and thus hold the shouldered portion I6 of the upper contact II of the fuse tube against the flat boss I8 formed on the upper portion of the door.

The upper contact I'I of the fuse tube is provided with a downwardly extending portion I9 providing an extensive surface against which the upper brush contact 4 bears. The latch means adjacent the upper portion of the fuse 'tube as` sembly may correspond with that disclosed in the above noted copending application, although obviously it may take many forms.

As disclosed in the copending application, the latch means may consist of a pair of relatively springy arms 20 which are provided with downwardly extending tongues 2I having bevelled inner edges against which pins 22 carried by the upper contact Il normally bear and thus hold the fuse tube assembly in its closed or operative position. In order to allow for the opening of the door, a pair of outwardly bowed cam members 23 are carried by the door and are located between the contact I1 and the lingers 2| so that When the door is pulled outwardly, the limited motion allowed between the door and fuse tube permits these cam members 23 to spread the arms 2I apart sufficiently to allow the pins 22 to pass outwardly therefrom. Also in closing the door,

Vvallow the pins 22 to pass back into the position shown in Figure 1.

A contact carrying lever 24 is pivotally mounted, as indicated at 25, upon the collar I3 and is provided with a notched lower portion 26 over which the fuse link 21 passes, the fuse link extending from the upper contact I'I and being clamped by the thumb nut or cap 28 in the usual manner to the upper contact and passing downwardly through theuse tube and outwardly through the lower end thereof. The other end of the fuse link is clamped by means of the thumb nut 29, as shown in Figures 1 and 2. If desired, the pintle pin, which in reality may consist of a pair of screws 25 may pivotally and simultaneously join the lever 24, the collar I3 and the ears I2.

The lever 24 is provided with a pair of outwardly projecting trunnions 30 which may have flattened portions if desired and which are tted within the hook hinge members 8, as shown in Figure 1, and thus provide the pivot means about which the fuse tube assembly is adapted to rock when moving to open position. Normally the lever 24 is held closely adjacent the fuse tube as the fuse link is clamped by the thumb nut 29 and holds the parts in this relative relation.

When the fuse link is ruptured, the fuse tube drops outwardly, rst moving to the position shown in dotted lines and extending at an angle to its initial position, the link 24 pivoting about the trunnions 30 and the fuse tube pivoting at 25 about the link 24.

After the pins 22 at the upper contact have cleared the members 2I by sliding downwardly, as indicated, the fuse tube assembly rocks to the lower dotted line position shown in Figure 1.

The lever 24 carries a contact nger 3l which is pivoted upon the pintle pin 32 and is urged by means of the spring 33 outwardly towards the brush or lower contact 5. Normally, however, the contact finger 3I is held within the slot of the lever 24 and the brush 5 bears directly against the broad face of the lever 24, 'thus making excellent contact. Of course, the brush 5 also may engage the contact linger 3I while this contact finger lies within the slot, as is obvious from Figure 1.

This contact linger is provided with a transverse lower portion 34 which bears against the fuse tube and tends to rock the lever 24 outwardly away from the fuse tube, such motion being resisted by the fuse link under normal conditions.

When, however, the fuse link blows, the lever 24 is free to rock outwardly and the contact finger 3I rocks outwardly with reference to the lever 24 and maintains contact with the stationary lower contact 5 an appreciable length of time, thus allowing the fuse tube to clear itself even under small overloads or slow burning conditions and maintaining contact with the stationary contact for an appreciable length of time and distance of travel of the lower portion of the fuse tube outwardly from the lower contact, thereby avoidi ing burning of the contact even under these severe conditions.

Also this contact nger, which is carried by the fuse tube assembly, not only maintains contact with the lower contact for an appreciable length of time, it being noted that contact with the upper stationary contact is also necessarily maintained for an appreciable length of time, as is obvious from Figure 1, but that also this contact finger assists in the initial opening motion of the device.

Additionally, the contact nger, by urging the lever 24 outwardly away from the fuse tube, serves to withdraw any remaining po'rtion of the fuse link and thus assists in extinguishing the arc within the fuse tube.

It is to be noted particularly that all of these functions are performed irrespective of the distance which the fuse tube assembly is allowed to drop, although it is preferable to allow the fuse tube assembly to drop to full open position.

Another function which this contact finger per- Vforms is that of .cushioning the fall of the fuse tube assembly. For example, when the fuse tube assembly rocks to the lower position shown in dotted lines in Figure 1, it is clear that the lever 24 contacts with the stops or ears 9 and that the lower end of the fuse tube swings upwardly and engages the portion 34 of the contact nger and thus cushions the fuse tube assembly as the downward rocking motion is now resisted by the spring 33 of the contact finger. If desired, the lever 24 may be widened by means of the extensions 24', such portions of the lever engaging the stops 9. It is preferable to provide the lever 24 with hook like extensions 3S, see Figure 1, which are located on opposite sides of the fuse tube and which rock beneath the lugs 9 and prevent inadvertent detachment of the fuse tube assembly Lli) while it is falling but allows removal when in full open position.

Further than this, the trunnions 30 are fiattened on one side so that when the fuse tube assembly is in its lowermost position, these flattened or narrower portions of the trunnions will,

facilitate removal of the trunnions from the hinge member 1. If desired, it is, of course, within the province and contemplated by this invention to so form the flattened portions as to preclude removal of the fuse tube assembly except in one or more predetermined positions.

It is to be noted also that the sector-shaped arms 3G prevent inadvertent removal of the fuse tube from the hinge members throughout a predetermined portion of the rocking motion of such fuse tube assembly.

It is believed that the flattened portions of the trunnions, which are shown in Figure l, are shown most clearly in Figure 4 for the trunnions -43hereinafter described in connection with the modied form of the invention.

In the form shown in Figures 4 and 5, the fuse tube 31 is provided with a lower collar 38 pvoted, as indicated at 39, to the door 40. A lever 4I corresponding to the lever 24 is pvoted, as indicated at 42, to the collar 38 and is provided with outwardly projecting trunnions 43, which may have flattened faces as previously described in connection with the trunnions 3|), which support the fuse tube assembly as previously described.

Also the lever 4I may be provided with side extensions 4i' corresponding to the side extensions 24 of the lever 24, as previously described. This lever is provided with outwardly projecting ears which carry a pintle pin 44 upon which the contact linger 45 is pivotally carried, a spring 46 being provided and urging the contact finger outwardly, as has been previously described.

The contact nger 45 is provided with a lower extension 41 which bears against the fuse tube and which receives the free end of the fuse link 48 and is provided with a clamping thumb nut 49.

The operation of this apparatus is substantially the same as previously described.

It will be seen that a novel form of drop-out fuse construction has been provided in which a contact finger is furnished and maintains contact with the stationary contact of the housing while the fuse tube assembly is moving towards open or inoperative position, and that this contact is maintained through a substantial period of time, allowing the fuse tube to fully clear itself before the contacts are opened.

It will be seen furtheLthat this contact iinger also assists in the initial opening motion of the apparatus and additionally acts as a cushioning member to cushion the fall of the fuse tube assembly.

Although this invention has been described in considerable detail, it is to be understood that such description is intended as illustrative rather than limiting, as the invention may be variously embodied and is `tobe interpreted as claimed.

We claim:

1. A drop-out fuse comprising a stationary body portion having stationary upper and lower contacts, a fuse tube assembly including a fuse tube having an upper contact normally detachably connected to the upper stationary contact, said fuse tube assembly having movable supporting means adjacent its lower end for normally supporting said fuse tube assembly, and a fuse link extending from the upper contact of the fuse tube through the fuse tube and to the movable supporting means and normally restraining said movable supporting means against motion with said fuse tube assembly having movable support- Y ing means adjacent its lower end for normally supporting said fuse tube assembly, and a fuse link extending from the upper contact of the fuse tube through the fuse tube and to the movable supporting means and normally restraining said movable supporting means against motion with respect to said fuse tube assembly, said movable supporting means including a yieldingly urged contact flnger for contacting with the lower of said stationary contacts, said contact nger urging the lower portion of said fuse tube assembly outwardly from said body portion and maintaining contact with said lower stationary contact for a predetermined distance of travel of the lower portion of said fuse tube assembly.

3. A drop-out fuse comprising a supporting body portion having stationary upper and lower contacts, a fuse tube assembly including a fuse tube and a fuse link therein, said fuse tube having an upper contact and a lower metallic portion, said contact and lower metallic portion being normally electrically joined by said fuse link,

and said fuse link restraining said fuse tube assembly from outward motion with respect to said body portion, and a contact finger carried by said lower metallic member and spring urged towards said lower stationary contact and maintaining contact therewith as said fuse tube assembly moves outwardly from said body portion.

4. In a fuse construction, the combination of a body portion having spaced stationary contacts, a fuse tube assembly movably held with reference to said body portion and including a fuse tube, a fuse link within said fuse tube normally forming a connecting member between the said stationary contacts and restraining the fuse tube assembly against outward motion with reference to said body portion, and a metallic contact finger urged outwardly towards said body portion and movable with respect to said fuse tube assembly and maintaining contact between said fuse tube assembly and one of said spaced contacts, while said fuse tube assembly is moving towards inoperative position.

5. A fuse of the class described comprising a body portion, stationary contacts carried by said body portion, an expulsion fuse assembly movably supported from said body portion and adapted to move outwardly from said body portion, mechanism movablyv supporting said fuse tube assembly, a fuse link normally restraining said mechanism against motion and normally forming an electrical connection between said stationary contacts, a yieldingly urged iinger carried by said mechanism for engaging one of said stationary contacts, said yieldingly urged linger allowing said iuse tube assembly to move a material distance with reference to said body portion without brcaking contact with the contact engaged by :aid yieldingly urged iingei'. v

G. A housed type fuse comprising a casing, stationary contacts carried by said casing, a door for said casing, an expulsion fuse secured to said door and having spaced contacts engaging said stationary contacts and having a fuse link normally joining said spaced contacts, lever mechanism for supporting said door and expulsion fuse adjacent the lower end thereof and restrained against motion by said fuse link, detachable means adjacent the upper portion of said casing for normally holding the upper end of said door closed, and a yieldingly urged contact linger carried by said lever mechanism for engaging the lower of said stationary contacts, one of said stationary contacts normally directly engaging said lever mechanism.

'7. A housed type fuse comprising a casing, stationary contacts carried by said casing, a door for said casing, anexpulsion fuse secured to said door and having spaced contacts engaging said stationary contacts and having a fuse link normally joining said spaced contacts, lever mechanisrn for supporting said door and expulsion fuse adjacent the lower end thereof and restrained against motion by said fuse link, detachable means adjacent the upper portion of said casing for normally holding the upper end of said door closed, and a yieldingly urged contact nger carried by said lever mechanism for engaging the lower of said stationary contacts, said lever mechanism when released by the expulsion of said fuse link rocking the lower end of said door and expulsion fuse outwardly, one of said stationary contacts normally directly engaging said lever mechanism.

8. A housed type fuse comprising a casing, a door for said casing, a fuse assembly carried by said door, pivot means supporting said door and fuse assembly, said fuse assembly having a fuse link, supporting means releasably holding said door closed, said supporting means being normally restrained against releasing movement by sad fuse link and being released when said fuse link is ruptured, said casing having stationary contacts and said fuse assembly having a yieldingly urged contact finger for engaging Aone of said stationary contacts, said fuse link normally forming means electrically connecting said stationary contacts.

9. A housed type fuse construction comprising a casing having spaced contacts, a door for said casing, a fuse tube secured to said door and having spaced contacts normally electrically connected to the spaced contacts of said casing, a fuse link carried within said fuse tube, means releasably holding said door closed, said fuse link holding said means against releasing, and a yieldingly pressed contact finger forming a portion of one of the contacts of said fuse tube for engaging the corresponding contact of said casing.

10. A housed type of drop-out fuse comprising a casing, stationary contacts carried by said casing, a door for said casing, an expulsion fuse secured to said door'and having spaced contacts engaging said stationary contacts and having a fuse link normally joining said spaced contacts, lever mechanism for supporting said door and expulsion fuse adjacent the lower end thereof and restrained against motion by said fuse link, detachable means adjacent the upper portion of said casing for normally holding the upper end of said door closed, and a yieldingly urged contact finger carried by said lever mechanism for engaging the lower of said stationary contacts, said lever mechanism when released by the expulsion of said fuse link first rocking the lower end of said door and expulsion fuse outwardly, said door and expulsion fuse thereafter moving downwardly and rocking outwardly from said casing, one of said stationary contacts directly engaging said lever when said fuse is in operative position.

11. A housed type of drop-out fuse comprising a casing, stationary contacts carried by said casing, a door for said casing, an expulsion fuse including a fuse tube secured to said door and having spaced contacts engaging said stationary contacts and having a fuse link normally joining said spaced contacts, lever mechanism for supportingsaid door and expulsion fuse adjacent the lower end thereof and restrained against motion by said fuse link, detachable means adjacent the upper portion of said casing for normally holding the upper end of said do-or closed, and a yieldingly urged contact finger carried by said lever mechanism for engaging the lower of said stationary contacts, said lever mechanism when released by the expulsion of said fuse link first rocking the lower end of said door and expulsion fuse outwardly, said door and expulsion fuse thereafter moving downwardly and rocking outwardly from said casing, said yieldingly urged contact finger forming a cushioning means for said fuse tube and door at the lower limit ofthe downward rocking motion thereof.

12. A housed type of fuse construction comprising acasing, stationary contacts carried by Said casing, a door for said casing, an expulsion fuse including a fuse tube secured to said door and having spaced contacts engaging said stationary contacts and having a fuse link normally joining said spaced contacts, lever mechanism for supporting said fuse tube and door adjacent the lower end thereof and restrained against motion by said fuse link, latching means adjacent the upper portion of said casingfor holding the upper end of said door closed, one of the spaced contacts of said fuse tube including a spring pressed contact nger having a portion adapted to engage one of the stationary contacts of said casing and having an extension bearing against said fuse tube and urging said lever mechanism away from said fuse tube.

13. A fuse of the type described comprising a body portion having stationary contacts, an expulsion fuse tube having spaced contacts normally engaging said stationary contacts and having an open end, a fuse link within said fuse tube electrically connecting said spaced contacts and extending through the open end of said fuse tube, and lever mechanism pivoted to said body portion and to said` fuse tube and normally holding said fuse tube in operative position, said lever mechanism being restrained from releasing motion by said fuse link, one of said spaced contacts including a contact finger for engaging one of said stationary contacts and yieldingly urged outwardly towards such stationary contact.

14. A fuse of the typedescribed comprising a body portion having stationary contacts, an expulsion fuse tube having spaced contacts normally engaging said stationary contacts and having an open end, a fuse link within said fuse tube electrically connecting said spaced contacts and extending through the open end of said fuse tube, and lever mechanism pivoted to said body portion and to said fuse tube and normally holding said fuse tube in operative position, said lever mechanism being restrained from releasing motion by said fuse link, one of said spaced contacts including a contact finger pivotally carried by said lever mechanism for engaging one of said stationary contacts and yieldingly urged outwardly towards such stationary contact, one of said stationary contacts normally engaging said lever mechanism.

15. A fuse of the type described comprising a body portion having stationary contacts, an expulsion fuse tube having spaced contacts normally engaging said stationaryl contacts and having an open end, a fuse link within said fuse tube electrically connecting said spaced contacts and extending through the open end of said fuse.

tube, and lever mechanism pivoted to said body portion and to said fuse tube and normally holding said fuse tube in operative position, said lever mechanism being restrained from releasing motion by said fuse link, one of said spaced contacts including a contact iinger pivotally carried by said lever mechanism for engaging one of said stationary contacts and yieldingly urged outwardly towards such stationary contact, said contact finger having an extension engaging said fuse tube and urging said lever mechanism away from said fuse tube when said lever mechanism is released upon blowing of said fuse link, one of said stationary contacts normally engaging said lever mechanism.

16. A housed type of drop-out fuse comprising a casing, stationary contacts carried by said casing, a door for said casing, an expulsion fuse tube assembly having spaced contacts normally engaging said stationary contacts and having a fuse link joining said spaced contacts, one oi said spaced contacts including lever mechanism for releasably supporting said fuse tube assembly and said door and` normally restrained trom releasing movement by said fuse link, and pivot means pivotally joining said lever mechanism to said fuse tube, said pivot means being operatively connected to said door.

17. A housed type of drop-out fuse comprising a casing, stationary contacts carried by said casing, a door for said casing, an expulsion fuse tube assembly having spaced contacts normally engaging said stationary contacts and having a fuse link joining said spaced contacts, one oi said spaced contacts including lever mechanism for releasably said fuse tubeA assemblyL and said door and normally restrained from releasing movement by said fuse link, said door having a pair of spaced ears, said fuse tube assembly including a collar located between said ears, and pivot means pivotally joining said lever mechanism to said collar.

18. A drop-out fuse comprising a supporting body portion provided with stationary contacts and having lower open hinge members, a fuse tube having spaced contacts normally engaging said stationary contacts, a fuse link electrically connecting said spaced contacts, and lever mechanism having trunnions pivotally carried within said hinge members, said lever mechanism pivotally and releasably holding said fuse tube in operative position and being normally restrained from releasing motion by said fuse link, said lever mechanism having crescent-shaped members interlocking with said hinge members to preclude the removal of said trunnions from said hinge members throughout a predetermined portion of the rocking motion of said lever mechanism.

19. A drop-out fuse comprising a supporting body portion provided with stationary contacts and having lower hinge members provided with restricted open portions, a fuse tube having spaced contacts normally engaging said stationary contacts, a fuse link electrically connecting said spaced contacts, and lever mechanism having trunnions pivotally carried wit-hin said hinge members, said lever mechanism pivotally and releasably holding said fuse tube in operative position and being normally restrained from releasing motion by said fuse link, said lever mechanism having crescent-shaped members interlocking with said hinge members to preclude the removal of said trunnions from said hinge members throughout a predetermined portion of the rocking motion oi.' said lever mechanism, said trunnions having flattened portions to facilitate removal through the open portions of said hinge members after said lever mechanism has passed through the said predetermined portion of its rocking motion.

WILLIAM O. SCHUL'I'Z.

ALWIN G. STEINMAYER. 

